Stationary peg or pulverizer for rotary beater mills



Feb. 10, 1953 w.'c. ROGERS ETAL 2,628,038

STATIONARY PEG 0R PULVERIZER FOR ROTARY BEATER MILLS Filed March 17,1950 I l I l -30 1 .l

INVENTOR5 WAYNE 6.190 519: ZEJ'TER H. BOLTON JR.

ATTORNEY Patented F eb. 10, 1953 g STATIONARY PEG OR PULVERIZER FORROTARY BEATER MILLS Wayne C. Rogers and Lester A. Bolton, Jr.,Worcester, Mass, assignors to Riley Stoker Corporation, Worcester, Mass,a corporation of Massachusetts Application March'17, 1950, Serial No.150,146

8 Claims. (01. 241-300) This invention relates to pulverizing apparatus,and more particularly to the construction of the stationary pegs orpulverizing elements in machines of the rotary beater type.

One machine of this type which has proven to be highly successfulcomprises a rotatable disk mounted within a stationary casing. Thematerial to be pulverized, for example coal, is carried through thecasing by means of an air current, and pulverization is brought about bythe action of interfitting stationary and revoluble impact pegs mountedon the casing wall and the rotor disk respectively. The stationary pegsare subjected to considerabl abrasive action, as well as to the impactof the coal and of any foreign bodies which may be mingled therewith.Consequently these pegs may become worn rather rapidly, and under somecircumstances they may even be broken in service.

It is accordingly one object of the invention to provide a novelconstruction for a pulverizing element which will have a far longer lifeof useful service than prior devices.

It is a further object of the invention to provide a pulverizing elementwhich is adapted to withstand abrasive action and impact withoutappreciable wear or damage throughout an extremely long period ofoperation.

It is a further object of the invention to provide'a pulverizing elementwhich can be manufactured at a cost that is low in comparison with thelength of service obtainable therefrom.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

In accordance with the invention there is provided a pulverizing elementcomprising a base portion adapted to be attached to a supportingstructure. This base portion is preferably in the form of a short peg ofhard metal cast into a flanged metal ferrule which serves to support thepeg at its inner end. The peg is preferably of approximately oval orlenticular cross section. On the outer end of the peg there is mounted apiece of strong tough metal forming an extension of the peg and havingon its front side a flat surface which preferably lies at approximatelyright angles with the major axis of the oval cross section of the peg.This extension piece is fastened to the peg by a tension member such asa screw or the like of strong tough metal which extends longitudinallythrough the peg. To the. said flat surface of the extension piece thereis secured a protective lining or armor plate comprising one or moreflat pieces of an extremely hard material, such as tungsten carbide. Thepeg is preferably formed on its outer end with a short integral lugwhich overlaps the inner edge of the armor plate.

Referring to the drawings illustrating one embodiment of the invention,and in which like reference numerals indicate like parts,

Fig. 1 is a longitudinal cross section through a stationary pulverizingelement, the section being taken on the line I-I of Fig. 2;

Fig. 2 is a front elevation of the pulverizing element as indicated bythe arrow 2 in Fig. 1, with a small portion of the device broken awayfor clearness of illustration;

Fig. 3 is a view taken in section on the line 33 of Fig. l;

Fig. 4 is a view taken in section on the line 44 of Fig. l; V

Fig. 5 is a fragmentary sectional view of a pulverizer with the improvedstationary elements mounted therein; and

Fig. 6 is a fragmentary elevation of the pulverizer cheek plate with theimproved stationary elements mounted thereon.

In Figs. 5 and 6 there is shown a portion of a pulverizer of the generaltype disclosed in the prior patent to Craig No. 1,714,080, granted May21, 1929. This machine comprises a casing 10 shaped to provide agenerally cylindrical pulverizin chamber l I within which there ismounted a. vertical disk i2 rotatabl about a horizontal axis. This diskdivides the chamber it into an inlet zone land an outlet zone l5 whichare connected by an annular passage it around the outer edge of thedisk. Wear plates l8 are mounted on the inlet zone side of the disk, andother wear plates I9 are mounted on the outlet zone side of the disk,these parts bein held in place by bolts 20. Certain of the plates 18 areprovided with integral impact members 22, and the plates 1 9 areprovided with integral impact members 23 and 24 arranged in twoconcentric circular rows around the axis of the disk. A vertical cheekplate 26 is mounted within the outlet zone I5 in a position adJacent thewall of the casing l0 and spaced appreciably from the rotor disk. Thischeek plate is provided with two concentric circular rows of openings 27around the axis of the disk, and within each opening there is mounted astationary pulverizing element 28. These elements 28, whichform thesubject matter of the present invention, extend from the cheek plate 26toward the rotor disk, and they interfit in known manner with therevolving elements 23 and 24. When the machin is in operation, a cloudof air and particles of coal (or other material being pulverized) willwhirl at high speed in the outlet zone l5 under the influence of therevolving elements 23 and 24. As the rapidly moving coal particlesstrike the stationary elements 28, these particles will be reduced to afine powder. This powder will be entrained by the air stream and thus becarried out of the pulveriizng chamber. During such operation thestationary elements 28 are subjected to severe abrasive action and tothe impact of rapidly traveling coal particles and foreign matter.

In order that the elements 28 may withstand such severe conditions, theyare constructed in a novel manner. Thus each element 28 comprises a baseportion in the form of a short peg 30 of a hard metal, such as whiteiron, cast into a flanged ferrule 31 of a strong resilient metal, suchas steel. This ferrule is located at the inner end ofthe peg and servesas a support for the peg. While the ferrule and the adjacent portion ofthe peg are circular, the remaining portion of the peg, which extendsoutwardly from the ferrule, is of approximately oval or lenticular Crosssection. An opening 33 extends longitudinally through the peg 33, theinner end of this opening being enlarged to form a counterbore 34. Theaxis of the opening 33 is parallel with the centerline of the peg andsomewhat offset therefrom in a rearward direction along the major axisof the oval cross section of the peg. On the outer end of the peg 30there is mounted an extension piece 33 formed of a strong tough metalsuch as steel. This piece 36 comprises a plate portion 3-! elongated inthe outward direction, the portion 3'! having a flat front surface 38generally aligned with the peg and extending at right angles with themajor axis of the oval cross section of the peg, and a-rib 43 extendinglongitudinally along the rear surface of the plate portion 31. At theinner end of the piece 36 there is provided a boss 4| having ascrew-threaded hole 42 therein aligned with the opening 33 in the peg30. A tension member in the form of a bolt or screw '44 extends throughthe opening 33 and into the hole 42 to engage the threads therein, theinner end of the screw having a head 45 thereon of the socket type whichlies within the counterbore 34. The screw 44 is preferably made of steelor other strong resilient material. The extension piece 33 is protectedfrom abrasion by means of armor plate 46 applied to its front face 38.This armor plate comprises three flat rectangular pieces of an extremelyhard material, preferably tungsten carbide in the cast form, althoughcemented tungsten carbide or other hard materials can be employed. Thearmor plate may be secured to the face 38 by silver soldering orbrazing. On the outer end of the peg 38 there is formed a small lug 48which lies in front of the armor 46 and slightly overlaps the inner edgethereof, this lug having a plane rear surface which lies close to thefront surface of the armor. In order that the elements 28 will beoriented properly when placed in the pulverizer, each opening 27 in thecheck plate 23 is provided with two diametrically opposed recesses 53,and each ferrule 3| is provided with two diametrically opposed radialbulges or projections 5i adapted to enter the recesses 53 at assemblyand to ensure that the major axes of the oval pegs will extendcircumferentially as shown in Fig. 6.

It will be apparent from Fig. 5 that the revolving impact members 23 and24 overlap the extension pieces 3'6 but not the pegs 30. When themachine is in operation there will be a zone of tremendous turbulence inthe region where these parts overlap, and the elements 28 will besubjected to very severe abrasive action from the material undergoingpulverization, as well as to the impact of particles of materialtraveling at very high speeds. Most of this abrasive action and impactis received directly by the armor plate 46, which is capable ofwithstanding such conditions for very long periods without appreciablewear. The armor protects the steel extension piece 33 from abrasion, andthe extension piece in turn provides the strength and resiliencenecessary to support the armor properly. In the case of a very heavyblow or impact on the armor 46, the bolt 44 may yield elastically,permitting the piece 36 to rock slightly to the rear, so that the shockmay readily be absorbed without physical damage to any of the parts. Thelug 33 performs a very important duty in shielding the inner edge of thearmor 46 from the abrasive particles and in this manner preventingundercutting of the material of the peg 30 by a concentrated stream ofSuch particles. It will be understood that while the white iron peg 30is hard, it does not even remotely approach the tungsten carbide armor46 in hardness. The oval shape of the pegs 33 has the effect of reducingthe eddy currents in the cloud of air and material traveling past thepegs, thereby providing a smoother flow for this cloud, with .lessabrasive wear on the pegs.

The invention provides a pulverizing element which is comparativelysimple and inexpensive to manufacture. It is constructed for the mostpart of steel and cast iron, which are inexpensive materials. While thearmor 46 is preferably of tungsten carbide, which is rather costly, onlya small quantity of this material is required. The improved puiverizingelement has a far greater life of useful service than any constructionheretofore employed for the purpose.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

1. A pulverizing element comprising a base portion in the form of a pegof hard cast metal adapted to be attached at its inner end to asupporting structure, an extension piece of a strong tough metalfastened to the outer end of the peg, the extension piece including aplate portion elongated in the outward direction and having asubstantially fiat front surfacegenerally aligned with the peg, asubstantially flat armor plate of extremely hard material fastened tothe said front surface in position to be subjected to severe abrasiveaction by material undergoing pulverization when the element is inservice, and a lug integral with the peg and projecting outwardlytherefrom in front of the inner portion of the armor plate.

2. A pulverizing element as set forth in claim 1, in which the lug isprovided with a flat rear surface which lies close to the inner portionof the front surface of the armor plate.

3. A pulverizing element comprising a base portion in the form of a pegof hard cast metal adapted to be attached at its inner end to asupporting structure and having an opening extending longitudinallytherethrough, an extensionpiece of a strong tough metal mounted on theouter end of the peg and having a substantially flat front surfacegenerally aligned with the peg, a

tension member extending through the said opening and connecting theinner portion of the peg to the inner portion of the extension piece,and a substantially fiat armor plate of extremely hard material fastenedto the said front surface in position to be subjected to severe abrasiveaction by material undergoing pulverization when the element is inservice.

4. A pulverizing element as set forth in claim 3, in which the tensionmember is in the form of a screw with a head at its inner end and screwthreads on its outer end which engage a screw threaded opening in theinner end of the extension piece.

5. A pulverizing element as set forth in claim 3, in which the tensionmember has a head on its inner end which fits Within a counterbore atthe inner end of the opening through the peg.

6. A pulverizing element comprising a base portion in the form of a pegof hard, cast metal adapted to be attached at its inner end to asupporting structure and having an opening extending longitudinallytherethrough, an extension piece of a strong tough metal mounted on theouter end of the peg and including a plate portion having asubstantially flat front surface generally aligned with the peg, a ribextending along the rear surface of the plate portion, and a boss at theinner end of the extension piece having a screw-threaded hole thereinaligned with the said opening. a screw extending through the saidopening and engaging the screw-threaded hole to fasten the extensionpiece to the peg, and a substantially flat armor plate of extremely hardmaterial fastened to the said front surface in position to be subjectedto severe abrasive action by material undergoing pulverization when theelement is in service.

'7. A pulverizing element comprising a base portion in the form of a pegof hard metal cast at its inner end into a. flanged circular metalferrule, an extension piece of a strong tough metal fastened to theouter end of the peg and having a substantially fiat front surfacegenerally aligned with the peg, and a substantially flat armor plate ofextremely hard material fastened to the said front surface in positionto be subjected to severe abrasive action by material undergoingpulverization when the element is in surface, the ferrule having one ormore small radial bulges adapted to engage recesses in a supportingstructure and to ensure correct orientation of the pulverizing elementwhen it is installed in a pulverizing machine.

8. A pulverizing element as set forth in claim 3, in which there isprovided a lug integral with the peg and projecting outwardly therefromin front of the inner portion of the armor plate.

WAYNE C. ROGERS. LESTER A. BOLTON, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,186,071 Bledsoe June 6, 19161,322,339 Plaisted Nov. 18, 1919 1,576,472 Riley Mar. 9, 1926 2,208,892Bukacek July 23, 1940 2,246,799 Holland-Letz June 24, 1941 FOREIGNPATENTS Number Country Date 432,024 Germany July 29, 1926 658,810Germany Apr. 13, 1938

